## TL;DR
Period 013 is a special period, not a normal month, and in SAP it only opens when the posting period record for account type S (G/L accounts) explicitly covers it for that fiscal year. Open transaction OB52, find the posting period variant assigned to your company code, and add or extend the S record so period 013 of the prior fiscal year is open, restricted by authorization group if your controls require it. Then repost the accrual in the same session. Do not open all periods to all account types just to clear this one error, because that also reopens A, D, K and M postings for the whole company code.

```text
"posting period 013 is not open for account type S" error in SAP when posting the month-end accrual
```

## Use this when
- SAP raises the period-not-open message on an FB50, FB01 or journal upload posting dated in special period 013.
- The posting is a legitimate year-end adjustment such as an accrual, audit adjustment or tax provision.
- Normal periods 1 to 12 posted fine for the same company code and account.

## Not for this skill when
- The error names the MM period or goods movements. That is the material period in MMPV, not the FI posting period.
- The period is closed deliberately pending audit sign-off. Get the close owner to approve opening it instead of working around the lock.

## Steps
1. Reproduce the posting in display or check mode and note the company code, posting date, fiscal year and account type S from the error detail. Verify: the error text and the document header agree on company code and fiscal year
2. In OB52, display the posting period variant for that company code and inspect the account type S row for the special periods range. Verify: you can see whether period 013 sits inside an open From period / To period range for the correct year
3. Confirm in the company code settings (global parameters) which posting period variant and fiscal year variant apply, so you edit the variant actually in use. Verify: the variant you are editing matches the one assigned to the company code
4. Extend the S record to include period 013 for the prior fiscal year only, using an authorization group if segregation of duties requires named posters only. Verify: OB52 saves the change and a test display shows 013 open for S and still closed for other account types
5. Repost the accrual document and check it in FB03, then run the trial balance for the special period. Verify: the document posts with a document number and the accrual appears in the period 013 balances

## Variant phrasings
### SAP period 13 not open special period posting
The short form controllers search when the year-end adjustment window opens.
### OB52 posting period variant account type S error
The transaction-focused phrasing for the configuration fix.
### posting period 013 is not open for account type S month-end accrual
The verbatim symptom with the accrual context kept.

Compatibility: SAP ECC 6.0 and SAP S/4HANA Finance, transactions OB52, FB50, FB01 and FBL3N, with standard or leading-ledger special periods 013 to 016.

## Why it happens
SAP separates normal periods from special periods so year-end adjustments can be booked after period 12 closes without reopening everyday posting. The period check runs against the posting period variant by account type, so a variant updated for assets or customers still blocks G/L postings until the S record is extended. Accruals dated into period 013 therefore fail even though the calendar and the MM period both look open.

## Edge cases / pitfalls
- Opening period 013 for the wrong fiscal year is the most common miss: a document dated 31 December belongs to the old year even when you post it in January.
- If your ledger uses 16 special periods, check whether the adjustment belongs in 013 or a later audit period before posting.
- Close the special period again once adjustments finish and record the open window in the close log for audit.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_sqw3UQ2gVoi96WxrdK5gNw